d={'name':'john','age':25,'courses':['Math','Physics']}
print(d)

print(d['name']) #不存在会报错
print(d.get('age'))#不存在返回None

print(d.get('address'))
print(d.get('address','Not Exist'))

for item in d.items():
    print(item)

for key,value in d.items():
    print(key,value,sep='-->')

